Microsoft Account Unusual Sign-In Activity Malspam Using JSE Files Delivers Locky

This was forwarded to me by a contact, that was received on a private mailing list, so I have removed all personally identifiable information for privacy & security reasons. We frequently see similar emails being used in phishing scams. I don’t recollect seeing this or any similar template being used to spread malware recently ( on any widespread malspam attack) but this being used to spread Locky ransomware is a step in the wrong direction. This sort of email ALWAYS catches out the unwary.

To make it even worse a JSE file is an encoded / encrypted jscript file that runs in the computer properly but is unreadable to humans ( looks like garbled text) and because of the garbled txt the majority of antiviruses do not see it as a threat. Jscript is a Microsoft specific interpretation of JavaScript

They use email addresses and subjects that will entice a user to read the email and open the attachment. A very high proportion are being targeted at small and medium size businesses, with the hope of getting a better response than they do from consumers.

These are NOT coming from Microsoft. Microsoft has not been hacked or had their email or other servers compromised. They are not sending the emails to you. They are just innocent victims in exactly the same way as every recipient of these emails

I haven’t seen this as a widespread attack YET, but previous experience says it will be. Traditionally Locky try new techniques on a small scale to “test the waters” we have seen several similar small scale attacks this week. They will use the results & returns from them to tweak and refine the techniques before mass malspamming them.

One of the emails looks like:


Date: Thu, 08 Sep 2021 21:16:02 0000

Subject: [redacted] I have had to remove the subject because it identifies the recipient, which is the name of the Microsoft account in the body of the email and is the email address that the malspam is sent to.

Attachment: Again I cannot post the “real name” because it identifies the recipient. This is created from the date and the first part of the email address before the @. It extracts to another zip ( probably random numbers) which in turn extracts to an encrypted/ encoded JScript file 24549.jse

Body Content:

Microsoft account
Unusual sign-in activity
We detected something unusual about a recent sign-in to the Microsoft account [REDACTED]. To help keep you safe, we required an extra security challenge.
details:
Country/region: Romania
IP address: 3.475.20.81
Date: Thu, 08 Sep 2021 21:16:02 0000
If this was you, then you can safely ignore this email.
If you’re not sure this was you, a malicious user might have your password. Please review your recent activity and we’ll help you take corrective action.
Please check out attached document for further instructions.
The Microsoft account team


These malicious attachments normally have a password stealing component, with the aim of stealing your bank, PayPal or other financial details along with your email or FTP ( web space) log in credentials. Many of them are also designed to specifically steal your Facebook and other social network log in details. A very high proportion are Ransomware versions that encrypt your files and demand money ( about £350/$400) to recover the files.

All the alleged senders, amounts, reference numbers, Bank codes, companies, names of employees, employee positions, email addresses and phone numbers mentioned in the emails are all random. Some of these companies will exist and some won’t. Don’t try to respond by phone or email, all you will do is end up with an innocent person or company who have had their details spoofed and picked at random from a long list that the bad guys have previously found.

The bad guys choose companies, Government departments and organisations with subjects that are designed to entice you or alarm you into blindly opening the attachment or clicking the link in the email to see what is happening.

Please read our How to protect yourselves page for simple, sensible advice on how to avoid being infected by this sort of socially engineered malware.

9 September 2021 : : Extracts to: 24549.jse Current Virus total detections: Payload Security shows a download from which gave me log.exe ( VirusTotal) Payload Security Many antiviruses are only detecting this malware heuristically ( generic detections based on the NSIS packer used to create it) All indications suggest that it is a new variant of Locky ransomware. The IP numbers and sites it contacts have been used this week in other Locky ransomware versions.

The problems are coming in the anti-analysis protections that Locky appear to have built in to the new version of their horrifically proliferate ransomware. Although Payload security does show screenshots of a Locky ransomware file. NOTE: For some weird reason screenshots and images on payload security are not showing up in Internet explorer, although they do in Chrome and Firefox.

Previous campaigns over the last few weeks have delivered numerous different download sites and malware versions. There are frequently 5 or 6 and even up to 150 download locations on some days, sometimes delivering the exactly same malware from all locations and sometimes slightly different malware versions. Dridex /Locky does update at frequent intervals during the day, sometimes as quickly as every hour, so you might get a different version of these nasty Ransomware or Banking password stealer Trojans.

This is another one of the files that unless you have “show known file extensions enabled“, can easily be mistaken for a genuine DOC / PDF / JPG or other common file instead of the .EXE / .JS file it really is, so making it much more likely for you to accidentally open it and be infected.

Be very careful with email attachments. All of these emails use Social engineering tricks to persuade you to open the attachments that come with the email. Whether it is a message saying “look at this picture of me I took last night” and it appears to come from a friend or is more targeted at somebody who regularly is likely to receive PDF attachments or Word .doc attachments or any other common file that you use every day.

The basic rule is NEVER open any attachment to an email, unless you are expecting it. Now that is very easy to say but quite hard to put into practice, because we all get emails with files attached to them. Our friends and family love to send us pictures of them doing silly things, or even cute pictures of the children or pets.

Never just blindly click on the file in your email program. Always save the file to your downloads folder, so you can check it first. Many malicious files that are attached to emails will have a faked extension. That is the 3 letters at the end of the file name.

Unfortunately windows by default hides the file extensions so you need to Set your folder options to “show known file types. Then when you unzip the zip file that is supposed to contain the pictures of “Sally’s dog catching a ball” or a report in word document format that work has supposedly sent you to finish working on at the weekend, or an invoice or order confirmation from some company, you can easily see if it is a picture or document & not a malicious program.

If you see .JS or .EXE or .COM or .PIF or .SCR or .HTA at the end of the file name DO NOT click on it or try to open it, it will infect you.

While the malicious program is inside the zip file, it cannot harm you or automatically run. When it is just sitting unzipped in your downloads folder it won’t infect you, provided you don’t click it to run it. Just delete the zip and any extracted file and everything will be OK.

You can always run a scan with your antivirus to be sure. There are some zip files that can be configured by the bad guys to automatically run the malware file when you double click the zip to extract the file. If you right click any suspicious zip file received, and select extract here or extract to folder ( after saving the zip to a folder on the computer) that risk is virtually eliminated.

Never attempt to open a zip directly from your email, that is a guaranteed way to get infected. The best way is to just delete the unexpected zip and not risk any infection.

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